The objective of the proposed work is to understand how cyclic AMP and calcium regulate cell function. The rat parotid gland is used as a model system. Our current working hypothysis is that cyclic AMP acts through a cyclic nucleotide dependent protein kinase and that calcium exerts its effects by interacting with calmodulin. The Calcium-calmodulin complex in turn interacts with a variety of biologically active proteins to modify their activity. Calcium-calmodulin regulated protein kinases appear to be present in the parotid. Thus regulation of parotid function by a mechanism involving cyclic AMP and calcium regulated protein phosphorylation is a focal point of the proposed work. Studies are underway to isolate and characterize both cyclic AMP and calcium-calmodulin regulated protein kinases in the rat parotid. The subcellular distribution of the protein kinases and their substrates is another area of active investigation.